Iterative NC program modification and energy saving for a CNC machine tool feed drive system with linear motors

Abstract

This study proposes a design of iterative learning contouring controller (ILCC) by considering actual contour error compensation (ACEC) to enhance the contouring performance of CNC machine tool feed drive systems with linear motors. The ACEC with linear and circular interpolation is designed to estimates contour error precisely. The proposed control iteratively modifies the numerical control (NC) programs for each drive axis to reduce a contour error. Hence, the proposed approach can be directly applied for a commercial CNC machine tool with linear motors currently in use without any modification of their original controllers. Both of linear and circular interpolations are verified by simulation in both air-cutting and machining condition. The simulation is conducted for a non-smooth rhombus and circular trajectory. The effectiveness of the proposed methods has been experimentally verified through a CNC machine tool with linear motors for a non-smooth rhombus trajectory. Experimental results show that the proposed controller could reduce the maximum and mean contour errors by 94.58% and 88.67% on average, respectively. The proposed method improved the control input variance by 37.9%, and consequently energy consumption was reduced by 11.7% compared with the original NC program.